Precipitation cover for an exhaust system

ABSTRACT

An apparatus for an exhaust system, the apparatus comprising a precipitation cover adapted to be positioned at least partially downstream of a tailpipe, relative to a direction of an exhaust gas flow. The precipitation cover comprises a first cover end and a second cover end. The first cover end is configured as a precipitation outlet, and the second cover end is configured as an exhaust gas outlet and a precipitation inlet. When the first cover end and the tailpipe are coupled together, the first cover end and the tailpipe cooperate so as to form a precipitation exit opening.

FIELD OF THE DISCLOSURE

The present disclosure relates to an apparatus for an exhaust system.More specifically, the present disclosure relates to an apparatuscomprising a precipitation cover for the exhaust system.

BACKGROUND OF THE DISCLOSURE

All engines—diesel, gasoline, propane, and natural gas—produce exhaustgas containing carbon monoxide, hydrocarbons, and nitrogen oxides. Theseemissions are the result of incomplete combustion. Diesel engines alsoproduce particulate matter. As more government focus is being placed onhealth and environmental issues, agencies around the world are enactingmore stringent emission's laws.

Because so many diesel engines are used in trucks, the U.S.Environmental Protection Agency and its counterparts in Europe and Japanfirst focused on setting emissions regulations for the on-road market.While the worldwide regulation of nonroad diesel engines came later, thepace of cleanup and rate of improvement has been more aggressive fornonroad engines than for on-road engines.

Manufacturers of nonroad diesel engines are expected to meet setemissions regulations. For example, Tier 3 emissions regulationsrequired an approximate 65 percent reduction in particulate matter (PM)and a 60 percent reduction in NO_(x) from 1996 levels. As a furtherexample, Interim Tier 4 regulations required a 90 percent reduction inPM along with a 50 percent drop in NO_(x). Still further, Final Tier 4regulations, which will be fully implemented by 2015, will take PM andNO_(x) emissions to near-zero levels.

To meet such emissions levels, at least a portion of the exhaust gasbeing emitted from many engines must pass through an aftertreatmentsystem. The aftertreatment system is configured to remove variouschemical compounds and particulate emissions, such as PM and NO_(x). Theaftertreatment system may comprise a NO_(x) sensor, which is configuredto produce a NO_(x) signal indicative of a NO_(x) content of exhaust gasflowing thereby. An ECU may use the NO_(x) signal to control, forexample, a combustion temperature of the engine and/or to control theamount of a reductant injected into the exhaust gas, so as to minimizethe level of NO_(x) entering the atmosphere.

However, a problem associated with NO_(x) sensors is that, if they comeinto contact with precipitation—such as rain, melted snow, or meltedice—they may be prone to sending inaccurate NO_(x) signals, and they mayeven be prone to complete failure. Complete failure may occur ifprecipitation contacts a sensor element of the NO_(x) sensor, causingthe sensor element to crack, especially if the exhaust gas superheatsthe precipitation (e.g., 800° C. and above). Such failures may lead tothe engine being derated, customer dissatisfaction, and expensiverepairs.

Therefore, what is needed in the art is an apparatus for minimizing theamount of precipitation that comes into contact with the NO_(x) sensor,while at the same time, minimizing the effect on the normal exhaustfunction (i.e., minimizing any back pressure). And what is additionallyneeded in the art is an apparatus that is cost effective, easy toimplement, does not require moving parts, and is visually appealing.

SUMMARY OF THE DISCLOSURE

Disclosed is an apparatus for an exhaust system, the apparatuscomprising a precipitation cover adapted to be positioned at leastpartially downstream of a tailpipe relative to a direction of an exhaustgas flow. The precipitation cover comprises a first cover end and asecond cover end. The first cover end is configured as a precipitationoutlet, and the second cover end is configured as an exhaust gas outletand a precipitation inlet. When the first cover end and the tailpipe arecoupled together, the first cover end and the tailpipe cooperate so asto form a precipitation exit opening.

The disclosed apparatus minimizes the amount of precipitation thatenters the tailpipe and, thus, the amount that comes into contact withthe NO_(x) sensor. At the same time, the disclosed apparatus onlyminimally interferes with the normal exhaust function of the engine(i.e., it minimizes any back pressure). And, further yet, it is costeffective, easy to implement, does not require moving parts, and isvisually appealing.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings refers to the accompanyingfigures in which:

FIG. 1 is a schematic illustration of a power system comprising anapparatus for an exhaust system;

FIG. 2 is an elevational view of a tailpipe and the apparatus, theapparatus comprising a precipitation cover and a spacer;

FIG. 3 is a partially exploded, perspective view of the tailpipe and theprecipitation cover and the spacer;

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 2, and itillustrates the precipitation cover and the spacer;

FIG. 5 is a view of a second embodiment of the apparatus taken from aview similar to that shown in FIG. 4;

FIG. 6 is an elevational view of a tailpipe and a third embodiment ofthe apparatus;

FIG. 7 is a sectional view taken along lines 6-6 of FIG. 6, and itillustrates a supplemental spacer; and

FIG. 8 is a sectional view taken along line 7-7 of FIG. 6, and itillustrates the spacer.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, there is shown a schematic illustration of a powersystem 100 comprising an apparatus 102 for an exhaust system 140. Theapparatus 102 may work particularly well in combination with, forexample, a NO_(x) sensor 119, but it would work just as well with anyengine, regardless of whether it has an aftertreatment system 120, aNO_(x) sensor 119, etc.

The power system 100 may be used for providing power to a variety ofmachines, including on-highway trucks, construction vehicles, marinevessels, stationary generators, automobiles, agricultural vehicles, andrecreation vehicles.

The engine 106 may be any kind of engine 106 that produces an exhaustgas, the exhaust gas being indicated by directional arrow 192. Forexample, engine 106 may be an internal combustion engine, such as agasoline engine, a diesel engine, a gaseous fuel burning engine (e.g.,natural gas) or any other exhaust gas producing engine. The engine 106may be of any size, with any number cylinders (not shown), and in anyconfiguration (e.g., “V,” inline, and radial). Although not shown, theengine 106 may include various sensors, such as temperature sensors,pressure sensors, and mass flow sensors.

The power system 100 may comprise an intake system 107. The intakesystem 107 may comprise components configured to introduce a freshintake gas, indicated by directional arrow 189, into the engine 106. Forexample, the intake system 107 may comprise an intake manifold (notshown) in communication with the cylinders, a compressor 112, a chargeair cooler 116, and an air throttle actuator 126.

Exemplarily, the compressor 112 may be a fixed geometry compressor, avariable geometry compressor, or any other type of compressor configuredto receive the fresh intake gas, from upstream of the compressor 112.The compressor 112 compress the fresh intake gas to an elevated pressurelevel. As shown, the charge air cooler 116 is positioned downstream ofthe compressor 112, and it is configured to cool the fresh intake gas.The air throttle actuator 126 may be positioned downstream of the chargeair cooler 116, and it may be, for example, a flap type valve controlledby an electronic control unit (ECU) 115 to regulate the air-fuel ratio.

Further, the power system 100 may comprise an exhaust system 140. Theexhaust system 140 may comprise components configured to direct exhaustgas from the engine 106 to the atmosphere. Specifically, the exhaustsystem 140 may comprise an exhaust manifold (not shown) in fluidcommunication with the cylinders. During an exhaust stroke, at least oneexhaust valve (not shown) opens, allowing the exhaust gas to flowthrough the exhaust manifold and a turbine 111. The pressure and volumeof the exhaust gas drives the turbine 111, allowing it to drive thecompressor 112 via a shaft (not shown). The combination of thecompressor 112, the shaft, and the turbine 111 is known as aturbocharger 108.

The power system 100 may also comprise, for example, a secondturbocharger 109 that cooperates with the turbocharger 108 (i.e., seriesturbocharging). The second turbocharger 109 comprises a secondcompressor 114, a second shaft (not shown), and a second turbine 113.Exemplarily, the second compressor 114 may be a fixed geometrycompressor, a variable geometry compressor, or any other type ofcompressor configured to receive the fresh intake flow, from upstream ofthe second compressor 114, and compress the fresh intake flow to anelevated pressure level before it enters the engine 106.

The power system 100 may also comprises an exhaust gas recirculation(EGR) system 132 that is configured to receive a recirculated portion ofthe exhaust gas, as indicated by directional arrow 194. The intake gasis indicated by directional arrow 190, and it is a combination of thefresh intake gas and the recirculated portion of the exhaust gas. TheEGR system 132 comprises an EGR valve 122, an EGR cooler 118, and an EGRmixer (not shown).

The EGR valve 122 may be a vacuum controlled valve, allowing a specificamount of the recirculated portion of the exhaust gas back into theintake manifold. The EGR cooler 118 is configured to cool therecirculated portion of the exhaust gas flowing therethrough. Althoughthe EGR valve 122 is illustrated as being downstream of the EGR cooler118, it could also be positioned upstream from the EGR cooler 118. TheEGR mixer is configured to mix the recirculated portion of the exhaustgas and the fresh intake gas into, as noted above, the intake gas.

As further shown, the exhaust system 140 may comprise an aftertreatmentsystem 120, and at least a portion of the exhaust gas passestherethrough. The aftertreatment system 120 is configured to removevarious chemical compounds and particulate emissions present in theexhaust gas received from the engine 106. After being treated by theaftertreatment system 120, the exhaust gas is expelled into theatmosphere via a tailpipe 178. The apparatus 102 comprises aprecipitation cover 129 adapted to be positioned at least partiallydownstream of a tailpipe 124 relative to a direction of the exhaust gasflow (see directional arrow 192).

The aftertreatment system 120 may comprise a NO_(x) sensor 119, theNO_(x) sensor 119 being configured to produce and transmit a NO_(x)signal to the ECU 115 that is indicative of a NO_(x) content of exhaustgas flowing thereby. The NO_(x) sensor 119 may, for example, rely uponan electrochemical or catalytic reaction that generates a current, themagnitude of which is indicative of the NO_(x) concentration of theexhaust gas.

The ECU 115 may have four primary functions: (1) converting analogsensor inputs to digital outputs, (2) performing mathematicalcomputations for all fuel and other systems, (3) performing selfdiagnostics, and (4) storing information. Exemplarily, the ECU 115 may,in response to the NO_(x) signal, control a combustion temperature ofthe engine 106 and/or the amount of a reductant injected into theexhaust gas, so as to minimize the level of NO_(x) entering theatmosphere.

Referring back to FIG. 1, as shown, the aftertreatment system 120comprises a diesel oxidation catalyst (DOC) 163, a diesel particulatefilter (DPF) 164, and a selective catalytic reduction (SCR) system 152.The SCR system 152 comprises a reductant delivery system 135, an SCRcatalyst 170, and an ammonia oxidation catalyst (AOC) 174. Exemplarily,the exhaust gas flows through the DOC 163, the DPF 164, the SCR catalyst170, and the AOC 174, and is then, as just mentioned, expelled into theatmosphere via the tailpipe 178.

In other words, in the embodiment shown, the DPF 164 is positioneddownstream of the DOC 163, the SCR catalyst 170 downstream of the DPF164, and the AOC 174 downstream of the SCR catalyst 170. The DOC 163,the DPF 164, the SCR catalyst 170, and the AOC 174 may be coupledtogether. Exhaust gas treated, in the aftertreatment system 120, andreleased into the atmosphere contains significantly fewerpollutants—such as diesel particulate matter, NO₂, and hydrocarbons—thanan untreated exhaust gas.

The DOC 163 may be configured in a variety of ways and contain catalystmaterials useful in collecting, absorbing, adsorbing, and/or convertinghydrocarbons, carbon monoxide, and/or oxides of nitrogen contained inthe exhaust gas. Such catalyst materials may include, for example,aluminum, platinum, palladium, rhodium, barium, cerium, and/or alkalimetals, alkaline-earth metals, rare-earth metals, or combinationsthereof. The DOC 163 may include, for example, a ceramic substrate, ametallic mesh, foam, or any other porous material known in the art, andthe catalyst materials may be located on, for example, a substrate ofthe DOC 163. The DOC(s) may also be configured to oxidize NO containedin the exhaust gas, thereby converting it to NO₂. Or, stated slightlydifferently, the DOC 163 may assist in achieving a desired ratio of NOto NO₂ upstream of the SCR catalyst 170.

The DPF 164 may be any of various particulate filters known in the artconfigured to reduce particulate matter concentrations, e.g., soot andash, in the exhaust gas to meet requisite emission standards. Anystructure capable of removing particulate matter from the exhaust gas ofthe engine 106 may be used. For example, the DPF 164 may include awall-flow ceramic substrate having a honeycomb cross-section constructedof cordierite, silicon carbide, or other suitable material to remove theparticulate matter. The DPF 164 may be electrically coupled to acontroller, such as the ECU 115, that controls various characteristicsof the DPF 164.

If the DPF 164 were used alone, it would initially help in meeting theemission requirements, but would quickly fill up with soot and need tobe replaced. Therefore, the DPF 164 is combined with the DOC 163, whichhelps extend the life of the DPF 164 through the process ofregeneration. The ECU 115 may be configured to measure the PM build up,also known as filter loading, in the DPF 164, using a combination ofalgorithms and sensors. When filter loading occurs, the ECU 115 managesthe initiation and duration of the regeneration process.

Moreover, the reductant delivery system 135 may comprise a reductanttank 148 configured to store the reductant. One example of a reductantis a solution having 32.5% high purity urea and 67.5% deionized water(e.g., DEF), which decomposes as it travels through a decomposition tube160 to produce ammonia. Such a reductant may begin to freeze atapproximately 12 deg F. (−11deg C.). If the reductant freezes when amachine is shut down, then the reductant may need to be thawed beforethe SCR system 152 can function.

The reductant delivery system 135 may comprise a reductant header 136mounted to the reductant tank 148, the reductant header 136 furthercomprising, in some embodiments, a level sensor 150 configured tomeasure a quantity of the reductant in the reductant tank 148. The levelsensor 150 may comprise a float configured to float at a liquid/airsurface interface of reductant included within the reductant tank 148.Other implementations of the level sensor 150 are possible, and mayinclude, exemplarily, one or more of the following: (a) using one ormore ultrasonic sensors; (b) using one or more optical liquid-surfacemeasurement sensors; (c) using one or more pressure sensors disposedwithin the reductant tank 148; and (d) using one or more capacitancesensors.

In the illustrated embodiment, the reductant header 136 comprises a tankheating element 130 that is configured to receive coolant from theengine 106, and the power system 100 may comprise a cooling system 133that comprises a coolant supply passage 180 and a coolant return passage181. A first segment 196 of the coolant supply passage 180 is positionedfluidly between the engine 106 and the tank heating element 130 and isconfigured to supply coolant to the tank heating element 130. Thecoolant circulates, through the tank heating element 130, so as to warmthe reductant in the reductant tank 148, therefore reducing the riskthat the reductant freezes therein. In an alternative embodiment, thetank heating element 130 may, instead, be an electrically resistiveheating element.

A second segment 197 of the coolant supply passage 180 is positionedfluidly between the tank heating element 130 and a reductant deliverymechanism 158 and is configured to supply coolant thereto. The coolantheats the reductant delivery mechanism 158, reducing the risk thatreductant freezes therein.

A first segment 198 of the coolant return passage 181 is positionedbetween the reductant delivery mechanism 158 and the tank heatingelement 130, and a second segment 199 of the coolant return passage 181is positioned between the engine 106 and the tank heating element 130.The first segment 198 and the second segment 199 are configured toreturn the coolant to the engine 106.

The decomposition tube 160 may be positioned downstream of the reductantdelivery mechanism 158 but upstream of the SCR catalyst 170. Thereductant delivery mechanism 158 may be, for example, an injector thatis selectively controllable to inject reductant directly into theexhaust gas. As shown, the SCR system 152 may comprise a reductant mixer166 that is positioned upstream of the SCR catalyst 170 and downstreamof the reductant delivery mechanism 158.

The reductant delivery system 135 may additionally comprise a reductantpressure source (not shown) and a reductant extraction passage 184. Thereductant extraction passage 184 may be coupled fluidly to the reductanttank 148 and the reductant pressure source therebetween. Exemplarily,the reductant extraction passage 184 is shown extending into thereductant tank 148, though in other embodiments the reductant extractionpassage 184 may be coupled to an extraction tube via the reductantheader 136. The reductant delivery system 135 may further comprise areductant supply module 168, and it may comprise the reductant pressuresource. Exemplarily, the reductant supply module 168 may be, or besimilar to, a Bosch reductant supply module, such as the one found inthe “Bosch Denoxtronic 2.2—Urea Dosing System for SCR Systems.”

The reductant delivery system 135 may also comprise a reductant dosingpassage 186 and a reductant return passage 188. The reductant returnpassage 188 is shown extending into the reductant tank 148, though insome embodiments of the power system 100, the reductant return passage188 may be coupled to a return tube via the reductant header 136.

The reductant delivery system 135 may comprise—among otherthings—valves, orifices, sensors, and pumps positioned in the reductantextraction passage 184, reductant dosing passage 186, and reductantreturn passage 188.

As mentioned above, one example of a reductant is a solution having32.5% high purity urea and 67.5% deionized water (e.g., DEF), whichdecomposes as it travels through the decomposition tube 160 to produceammonia. The ammonia reacts with NO_(x) in the presence of the SCRcatalyst 170, and it reduces the NO_(x) to less harmful emissions, suchas N2 and H2O. The SCR catalyst 170 may be any of various catalystsknown in the art. For example, in some embodiments, the SCR catalyst 170may be a vanadium-based catalyst. But in other embodiments, the SCRcatalyst 170 may be a zeolite-based catalyst, such as a Cu-zeolite or aFe-zeolite.

The AOC 174 may be any of various flowthrough catalysts configured toreact with ammonia to produce mainly nitrogen. Generally, the AOC 174 isutilized to remove ammonia that has slipped through or exited the SCRcatalyst 170. As shown, the AOC 174 and the SCR catalyst 170 may bepositioned within the same housing. But in other embodiments, they maybe separate from one another.

The precipitation cover 129 comprises a first cover end 110 and a secondcover end 117. The first cover end 110 is configured as a precipitationoutlet, and the second cover end 117 is configured as an exhaust gasoutlet and a precipitation inlet. As shown, for example, in FIGS. 2-3,when the first cover end 110 and the tailpipe 124 are coupled together,the first cover end 110 and the tailpipe 124 cooperate so as to form aprecipitation exit opening 171. In some embodiments, including the oneillustrated in FIGS. 2-4, the first cover end 110 and an end 147 of thetailpipe 124 cooperate, so as to form the precipitation exit opening171. The precipitation cover 129 and the precipitation exit opening 171are configured so as to minimize the amount of precipitation 165 thatenters the tailpipe 124 and that, ultimately, comes into contact withthe NO_(x) sensor 119.

At least a portion of the first cover end 110 may be positioned radiallyoutside of an end 147 of the tailpipe 124. For example, as illustrated,the precipitation cover 129 and the tailpipe 124 may both be tubularlyshaped, wherein an inner diameter 154 of the precipitation cover 129 maybe larger than an outer diameter 159 of the tailpipe 124. In otherembodiments, the precipitation cover 129 and/or the tailpipe 124 maytake other shapes, such as an extended square shapes, extended oblongshapes, and so forth.

Further, the precipitation cover 129 may comprise a hood 162 extendingaxially away from the second cover end 117. The hood 162 may beangularly aligned with a spacer 125 relative to the imaginary cover axis153. The hood 162 may minimize the amount of precipitation 165 thatenters the precipitation cover 129 and tailpipe 124, particularly if theprecipitation 165 is falling in the direction shown in FIG. 2, forexample. The hood 162 is illustrated as having a smooth, round contour,but other embodiments could take various different shapes, assuming thatthe hood 162 maintains its functionality (i.e., minimizing the amount ofprecipitation 165 that enters the precipitation cover 129 and tailpipe124).

The tailpipe 124 may further comprise a first tailpipe section 128 and asecond tailpipe section 139. The second tailpipe section 139 may besubstantially elbow shaped and may be positioned downstream of the firsttailpipe section 128, relative to the direction of the exhaust gas flow.The first tailpipe section 128 may define an imaginary tailpipe axis142, and the precipitation cover 129 may define an imaginary cover axis153. And as shown in FIG. 2, the imaginary tailpipe axis 142 and theimaginary cover axis 153 may define an angle 156 therebetween in a rangeof 90° and 150°, and in some embodiments, it may be between 110° and130°. The angle 156 may be such that it prevents precipitation 165 fromentering the tailpipe 124, even when the precipitation 165 is fallingat, for example, a 40° angle.

The precipitation cover 129 may be made of, for example, aluminizedsteel or stainless steel. Aluminized steel provides a surface thatpaints stick to, even when the aluminized steel is very hot, and thealuminized steel does not rust, even if the paint is scratched offthereof. Likewise, the first tailpipe section 128, the second tailpipesection 139, and the spacer 125 may also be made of, for example, eitheraluminized steel or stainless steel.

As shown, in FIG. 2, the precipitation cover 129 may overlap thetailpipe 124 so as to form an overlapped region 172, and theprecipitation cover 129 and the tailpipe 124 may be spaced apart, alongthe overlapped region 172, so as to form an annular gap 146therebetween.

The apparatus 102 may further comprise a spacer 125 mounted to thetailpipe 124, and the precipitation cover 129 may be mounted to thespacer 125. Or, more specifically, the spacer 125 may be mounted to anouter surface 157 of the tailpipe 124, and the precipitation cover 129may be mounted to an outer surface 157 of the spacer 125. As illustratedin, for example, FIG. 3, the imaginary tailpipe axis 142 and theimaginary cover axis 153 may define a plane 131, and the spacer 125 andthe precipitation cover 129 may be symmetric to one another relative tothe plane 131.

As shown, in FIG. 4, the spacer 125 may be “horseshoe shaped” and maypartially extend around the outer surface 157 of the tailpipe 124. Forexample, the spacer 125 may extend around approximately 270° about thetailpipe 124 (see angle 138), though in other embodiments, the spacer125 may extend around a smaller or larger angle. In other embodiments,the spacer 125 may comprise multiple pieces and take a number ofdifferent shapes, and it may comprise holes, slots, and the like.

As shown in FIG. 4, a first end surface 176 of the spacer 125 mayconnect an inner surface 175 and an outer surface 187 of the spacer 125.A second end surface 177 of the spacer 125 may also connect the innersurface 175 and the outer surface 187. The first end surface 176, thesecond end surface 177, the inner surface 175 of the precipitation cover129, and the outer surface 187 of the tailpipe 124 may cooperate so asto define the precipitation exit opening 171.

Referring to FIG. 5, there is shown a view of a second embodiment of theapparatus 202 taken from a view similar to that which is shown in FIG. 4(though FIG. 4 is a view of the first embodiment of the apparatus 102).The apparatus 202 has many components similar in structure and functionas the apparatus 102, as indicated by the use of identical referencenumerals where applicable. However, a difference, between the apparatus202 and the apparatus 102, is that the spacer 225 of the apparatus 202is a bead of weld (see, for example, the bead of weld 234), rather than,for example, a plate. And as shown, in the illustrated embodiment of theapparatus 202, there is also a bead of weld 227 and a bead of weld 291.Such an embodiment may provide robust support of the precipitation cover129, while simultaneously keeping assembly and manufacturing costs low.Other embodiments of the apparatus 202 may have a greater or lessernumber of welds, and they may be oriented differently, relative to oneanother.

Referring to FIGS. 6-8, there is shown a third embodiment of anapparatus 302. The third embodiment of the apparatus 302 has manycomponents similar in structure and function as the first embodiment ofthe apparatus 102 and the second embodiment of the apparatus 202.However, in the third embodiment of the apparatus 302, the precipitationcover 329 may comprise a base cover 321 and an extended cover 323. Thebase cover 321 may be positioned substantially downstream of an end 147of the tailpipe 124 relative to a direction of the exhaust gas flow, andthe extended cover 323 may be positioned substantially upstream of theend 147 of the tailpipe 124 relative to a direction of the exhaust gasflow. One potential advantage of the precipitation cover 329 is thatoperators of, for example, a work machine may find it more visuallyappealing.

As shown in FIGS. 6-7, exemplarily, the apparatus 302 may furthercomprise a supplemental spacer 379. The supplemental spacer 379 may bemounted to the tailpipe 124, and the precipitation cover 329 may bemounted to the supplemental spacer 379. Further, the supplemental spacer379 may be positioned downstream of the spacer 325 relative to thedirection of the exhaust gas flow. The precipitation cover 329 mayoverlap the tailpipe 124 so as to form an overlapped region 372, and theprecipitation cover 329 and the tailpipe 124 may be spaced apart fromone another, along the overlapped region 372, so as to form an annulargap 346 therebetween.

As shown in FIG. 7, the supplemental spacer 379 may be “horseshoeshaped” and may partially extend around the outer surface 157 of thetailpipe 124. For example, the supplemental spacer 379 may extend aroundapproximately 270° of the tailpipe 124 (see angle 393). In otherembodiments, the supplemental spacer 379 may comprise multiple piecesand take a number of different shapes, and it may comprise holes, slots,and the like.

In the embodiment illustrated in FIG. 7, a first end surface 303 of thesupplemental spacer 379 connects an inner surface 304 and an outersurface 305 of the supplemental spacer 379. And a second end surface 395of the supplemental spacer 379 connects the inner surface 304 and theouter surface 305 of the supplemental spacer 379. The first end surface303, the second end surface 395, the inner surface 304 of theprecipitation cover 329, and the outer surface 157 of the tailpipe 124cooperate so as to define a supplemental precipitation exit opening 383.

Finally, in the embodiment illustrated in FIG. 8, a first end surface376 of the spacer 325 may connect an inner surface 375 and an outersurface 387 of the spacer 325. A first end surface 376 of the spacer 325may connect an inner surface 375 and an outer surface 387 of the spacer325, and a second end surface 377 of the spacer 325 may also connect theinner surface 375 and the outer surface 387. As illustrated, the firstend surface 376, the second end surface 377, the inner surface 375, andthe outer surface 387 may cooperate so as to define the precipitationexit opening 371.

Further, the spacer 325 may be “horseshoe shaped” and may partiallyextend around the outer surface 157 of the tailpipe 124. For example,the spacer 325 may extend around approximately 270° of the tailpipe 124(see angle 393), though the spacer 325 may extend around a smaller or alarger angle. In other embodiments, the spacer 325 may comprise multiplepieces and take a number of different shapes, and it may comprise holes,slots, and the like.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such illustration and description isto be considered as exemplary and not restrictive in character, it beingunderstood that illustrative embodiments have been shown and describedand that all changes and modifications that come within the spirit ofthe disclosure are desired to be protected. It will be noted thatalternative embodiments of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations that incorporate one or more ofthe features of the present disclosure and fall within the spirit andscope of the present invention as defined by the appended claims.

1. An apparatus for an exhaust system, the apparatus comprisingprecipitation cover adapted to be positioned at least partiallydownstream of a tailpipe relative to a direction of an exhaust gas flow,the precipitation cover comprising a first cover end and a second coverend, the first cover end configured as a precipitation outlet, thesecond cover end configured as an exhaust gas outlet and a precipitationinlet, wherein when the first cover end and the tailpipe are coupledtogether, the first cover end and the tailpipe cooperate so as to form aprecipitation exit opening.
 2. The apparatus of claim 1, wherein theprecipitation cover comprises a base cover and an extended cover, thebase cover being positioned substantially downstream of an end of thetailpipe relative to a direction of the exhaust gas flow, the extendedcover being positioned substantially upstream of the end of the tailpiperelative to a direction of the exhaust gas flow.
 3. The apparatus ofclaim 1, wherein the precipitation cover and the tailpipe are bothtubularly shaped, and an inner diameter of the precipitation cover islarger than an outer diameter of the tailpipe.
 4. The apparatus of claim1, wherein the precipitation cover further comprises a hood extendingaxially from the second cover end.
 5. The apparatus of claim 1, whereinthe first cover end and an end of the tailpipe cooperate so as to formthe precipitation exit opening.
 6. The apparatus of claim 1, wherein atleast a portion of the first cover end is positioned radially outside ofan end of the tailpipe.
 7. The apparatus of claim 1, wherein thetailpipe further comprises a first tailpipe section and a secondtailpipe section, the first tailpipe section defining an imaginarytailpipe axis, the second tailpipe section being substantially elbowshaped and is positioned downstream of the first tailpipe sectionrelative to the direction of the exhaust gas flow, the precipitationcover defining an imaginary cover axis, and the imaginary tailpipe axisand the imaginary cover axis defining an angle therebetween in a rangeof 90° and 150°.
 8. The apparatus of claim 1, wherein the angletherebetween is in a range of between 110° and 130°.
 9. The apparatus ofclaim 1, wherein the precipitation cover overlaps the tailpipe so as toform an overlapped region.
 10. The apparatus of claim 9, wherein theprecipitation cover and the tailpipe are spaced apart, along theoverlapped region, so as to form an annular gap therebetween.
 11. Theapparatus of claim 1, further comprising a spacer mounted to thetailpipe, the precipitation cover being mounted to the spacer.
 12. Theapparatus of claim 11, wherein the spacer is “horseshoe shaped.”
 13. Theapparatus of claim 11, wherein the spacer is a bead of weld.
 14. Theapparatus of claim 11, wherein the tailpipe further comprises a firsttailpipe section and a second tailpipe section, the first tailpipesection defines an imaginary tailpipe axis, the second tailpipe sectionis substantially elbow shaped and is positioned downstream of the firsttailpipe section relative to the direction of the exhaust gas flow, theprecipitation cover defines an imaginary cover axis, the imaginarytailpipe axis and the imaginary cover axis define a plane, and thespacer is symmetric relative to the plane.
 15. The apparatus of claim11, wherein: a first end surface of the spacer connects an inner surfaceof the spacer and an outer surface of the spacer; a second end surfaceconnects the inner surface of the spacer and the outer surface of thespacer; and the first end surface of the spacer and the second endsurface of the spacer and the inner surface of the precipitation coverand the outer surface of the tailpipe cooperate so as to define theprecipitation exit opening.
 16. The apparatus of claim 15, wherein thespacer is mounted to an outer surface of the tailpipe, and theprecipitation cover is mounted to an outer surface of the spacer. 17.The apparatus of claim 15, wherein the spacer partially extends aroundthe outer surface of the tailpipe.
 18. The apparatus of claim 11,further comprising a supplemental spacer, the supplemental spacer beingmounted to the tailpipe, the precipitation cover being mounted to thesupplemental spacer, and the supplemental spacer being positioneddownstream of the spacer relative to the direction of the exhaust gasflow.
 19. The apparatus of claim 18, wherein: a first end surface of thesupplemental spacer connects an inner surface of the supplemental spacerand an outer surface of the supplemental spacer; a second end surface ofthe supplemental spacer connects the inner surface of the supplementalspacer and the outer surface of the supplemental spacer; and the firstend surface of the supplemental spacer and the second end surface of thesupplemental spacer and the inner surface of the precipitation cover andthe outer surface of the tailpipe cooperate so as to define asupplemental precipitation exit opening.
 20. An apparatus for an exhaustsystem, the apparatus comprising precipitation cover and a spacer, theprecipitation cover adapted to be positioned at least partiallydownstream of a tailpipe relative to a direction of an exhaust gas flow,the precipitation cover comprising a first cover end and a second coverend, the first cover end configured and a precipitation outlet, thesecond cover end configured as an exhaust gas outlet and a precipitationinlet, the spacer being mounted to the tailpipe, the precipitation coverbeing mounted to the spacer, wherein: when the first cover end and thetailpipe are coupled together, the first cover end and the tailpipecooperate so as to form a precipitation exit opening; the precipitationcover overlaps the tailpipe so as to form an overlapped region; theprecipitation cover and the tailpipe are spaced apart, along theoverlapped region, so as to form an annular gap therebetween; and theprecipitation cover further comprises a hood extending axially from thesecond cover end.